The present invention relates to a motor wherein current paths to windings are altered with a plurality of transistors without using position detecting elements.
In recent years, motors wherein current paths are altered electronically with a plurality of transistors have been used widely as drive motors for office automation apparatuses and audio-visual apparatuses. These motors are included in disk drive apparatuses, such as optical disk drive apparatuses (DVD apparatuses, CD apparatuses, etc.) and magnetic disk drive apparatuses (HDD apparatuses, FDD apparatuses, etc.). A motor wherein current paths to windings are altered with PNP-type bipolar power transistors and NPN-type bipolar power transistors is available as an example of the above-mentioned motors.
FIG. 28 shows a conventional motor, and its operation will be described below. A rotor 2011 has a field part formed by a permanent magnet. Three position detecting elements of a position detector 2041 detect the magnetic field of the field part of the rotor 2011. In other words, the position detector 2041 generates two sets of voltage signals, Kp1, Kp2 and Kp3, and Kp4, Kp5 and Kp6, from the three-phase output signals of the three position detecting elements in response to the rotation of the rotor 2011. A first distributor 2042 generates three-phase low-side signals Lp1, Lp2 and Lp3 responding with the voltage signals Kp1, Kp2 and Kp3 respectively to control the activation of low-side NPN-type bipolar power transistors 2021, 2022 and 2023. A second distributor 2043 generates three-phase high-side signals Mp1, Mp2 and Mp3 responding with the voltage signals Kp4, Kp5 and Kp6 respectively to control the activation of high-side PNP-type bipolar power transistors 2025, 2026 and 2027. As a result, three-phase drive voltages are supplied to windings 2012, 2013 and 2014.
In this conventional configuration, it is a problem that power losses of the power transistors are large. This is because that the NPN-type bipolar power transistors 2021, 2022 and 2023 and the PNP-type bipolar power transistors 2025, 2026 and 2027 supply drive voltages having necessary amplitudes to the windings 2012, 2013 and 2014 by controlling the voltage drop across the emitter and the collector in an analog manner. When the drive voltages are supplied, a voltage drop in each bipolar power transistor is large. As a result, a large power loss produced by the product value of the voltage drop and the drive current to the winding is caused, resulting in a large heat generation. To reduce this power loss, it is known to perform PWM drive (pulse drive voltages are supplied to the windings). For example, U.S. Pat. No. 5,982,118 discloses an example wherein a method of PWM-controlling power transistors by using two sensor outputs is used to reduce power losses.
However, the above-mentioned conventional example and U.S. Pat. No. 5,982,118 include three or two position detecting elements for detecting the rotational position of the rotor. For this reason, the spaces, connecting wires, etc. for the position detecting elements are required and become complicated, resulting in a high cost.
On the other hand, it is known that sensorless drive is performed to eliminate position detecting elements. U.S. Pat. No. 5,122,715 and U.S. Pat. No. 5,473,232 disclose a motor wherein the terminal voltages of windings are detected and current paths to the windings are altered in response to the timing of the detection. In U.S. Pat. No. 5,122,715, the width of activation has an electrical angle of 120 degrees, thereby having disadvantages of a large vibration and a large acoustic noise. The patent also discloses a complicated configuration having a switching regulator. In U.S. Pat. No. 5,473,232, power losses are reduced by making PWM switching of power transistors. However, the width of the activation for each power transistor has an electrical angle of120 degrees, thereby having disadvantages of a large vibration and a large acoustic noise.
It is therefore an object of the present invention to provide a motor capable of solving one or all of the above-mentioned problems.
The motor in accordance with the main aspect of the present invention comprises:
a rotor which has a field part generating field fluxes;
Q-phase windings (Q is an integer of 3 or more);
voltage supplying means which includes two output terminals for supplying a DC voltage;
power supplying means having Q first FET power transistors and Q second FET power transistors for supplying a power to said Q-phase windings, each of said Q first FET power transistors forming a current path between one output terminal side of said voltage supplying means and one of said Q-phase windings, and each of said Q second FET power transistors forming a current path between the other output terminal side of said voltage supplying means and one of said Q-phase windings;
voltage detecting means for producing a detected pulse signal in response to terminal voltages of said Q-phase windings;
state shifting means for shift-holding a holding state from one state to at least one other state in sequence in response to the detected pulse signal of said voltage detecting means;
activation control means for controlling active periods of said Q first FET power transistors and said Q second FET power transistors in response to said holding state;
commanding means for producing a command signal in response to an output pulse signal of said voltage detecting means; and
switching operation means for causing at least one of said Q first FET power transistors and said Q second FET power transistors to perform high-frequency switching in response to said command signal;
and that
said activation control means produces Q-phase first activation control signals and Q-phase second activation control signals in response to said holding state of said state shifting means for controlling said active periods of said Q first FET power transistors and said Q second FET power transistors, each of said active periods being an electrical angle which is larger than 360/Q degrees,
said switching operation means produces a switching pulse signal in response to said command signal, and makes high-frequency switching operation of at least one FET power transistor among said Q first FET power transistors and said Q second FET power transistors in response to said switching pulse signal, and
said state shifting means includes:
adjusting means for producing a timing signal after an adjust time from detection of said detected pulse signal,
shift hold means for shift-holding said holding state in response to said timing signal, and
adjust changing means for changing said adjust time of said adjusting means smaller in case that said command signal is larger than a predetermined value, thereby making the product value of said adjust time and said rotational speed of said rotor smaller in said case.
With this configuration, the switching operation means causes at least one of the FET power transistors of the power supplying means to perform high-frequency switching operation in response to the command signal. Therefore, power losses at the FET power transistors of the power supplying means can be reduced significantly, whereby the power efficiency of the motor can be improved greatly.
The voltage detecting means produces the detected pulse signal in response to the terminal voltages of the windings, the state shifting means shifts the phases of the activation to the windings in response to the detected pulse signal, and the activation control means control the active periods of the FET power transistors so as to rotate the rotor in a predetermined direction. Therefore, no position detecting element is required, and the configuration of the motor becomes simplified.
When the command signal of the commanding means becomes larger than a predetermined value, the adjust time to the output of the timing signal from the detected pulse signal is changed so that the product value of the adjust time and the rotational speed of the rotor becomes smaller. Hence, the active periods of the FET power transistors become shortened. Since the command signal becomes larger than the predetermined value during a rotor acceleration period, the active periods of the FET power transistors become shorter. As a result, the voltage detecting means can be prevented from detecting improperly the terminal voltages of the windings, and a stable acceleration can be attained easily.
Further, since the command signal also becomes larger than the predetermined value because of a large load torque, the active periods of the FET power transistors become shorter. As a result, the voltage detecting means can be prevented from detecting improperly the terminal voltages of the windings, and a stable rotation can also be attained even when a load torque is large.
The command signal becomes smaller than the predetermined value during a stable speed control period, and the adjust time becomes longer. Therefore, the active periods (the active electrical angles) of the FET power transistors are made considerably longer than an electrical angle of 360/Q degrees. As a result, the activation widths of the windings are made larger. It is thus possible to reduce acoustic noise and vibration of the motor with a stable rotation.
Since the change operation of the adjust time is carried out in response to the command signal, it is not necessary to provide new connecting wires for the change operation extended from the commanding means such as a speed control circuit. The configuration of the motor can thus be simplified. As a result, a motor performing a stable sensorless operation with reduced power loss, reduced vibration and reduced acoustic noise can be attained at a low cost according to the present invention.
The motor in accordance with another aspect of the present invention comprises:
a rotor which has a field part generating field fluxes;
Q-phase windings (Q is an integer of 3 or more);
voltage supplying means which includes two output terminals for supplying a DC voltage;
power supplying means having Q first FET power transistors and Q second FET power transistors for supplying a power to said Q-phase windings, each of said Q first FET power transistors forming a current path between one output terminal side of said voltage supplying means and one of said Q-phase windings, and each of said Q second FET power transistors forming a current path between the other output terminal side of said voltage supplying means and one of said Q-phase windings;
voltage detecting means for producing a detected pulse signal in response to terminal voltages of said Q-phase windings;
state shifting means for shift-holding a holding state from one state to at least one other state in sequence in response to the detected pulse signal of said voltage detecting means;
activation control means for controlling active periods of said Q first FET power transistors and said Q second FET power transistors in response to said holding state;
commanding means for producing a command signal in response to an output pulse signal of said voltage detecting means; and
switching operation means for causing at least one of said Q first FET power transistors and said Q second FET power transistors to perform high-frequency switching in response to said command signal;
and that
said activation control means produces Q-phase first activation control signals and Q-phase second activation control signals in response to said holding state of said state shifting means for controlling said active periods of said Q first FET power transistors and said Q second FET power transistors, each of said active periods being an electrical angle which is larger than 360/Q degrees,
said switching operation means produces a switching pulse signal in response to said command signal, and makes high-frequency switching operation of at least one FET power transistor among said Q first FET power transistors and said Q second FET power transistors in response to said switching pulse signal, and
said state shifting means includes:
adjusting means for producing a first timing signal after a first adjust time from detection of said detected pulse signal and a second timing signal after a second adjust time from detection of said detected pulse signal, said second adjust time being larger than said first adjust time,
shift hold means for shift-holding said holding state from a first state to a second state after said first adjust time from detection of said detected pulse signal in response to said first timing signal, and further shift-holding said holding state from said second state to a third state after said second adjust time from detection of said detected pulse signal in response to said second timing signal, and
adjust changing means for changing at least said second adjust time of said adjusting means smaller in case that said command signal is larger than a predetermined value, thereby making the product value of said second adjust time and said rotational speed of said rotor smaller in said case.
With this configuration, the switching operation means causes at least one of the FET power transistors of the power supplying means to perform high-frequency switching operation in response to the command signal. Therefore, power losses at the FET power transistors of the power supplying means can be reduced significantly, whereby the power efficiency of the motor can be improved greatly.
The voltage detecting means produces the detected pulse signal in response to the terminal voltages of the windings, the state shifting means shifts the phases of the activation to the windings in response to the detected pulse signal, and the activation control means control the active periods of the FET power transistors so as to rotate the rotor in a predetermined direction. Therefore, no position detecting element is required, and the configuration of the motor becomes simplified.
When the command signal of the commanding means becomes larger than a predetermined value, the second adjust time to the output of the second timing signal from the detected pulse signal is changed so that the product value of the adjust time and the rotational speed of the rotor becomes smaller. Hence, the active periods of the FET power transistors become shortened. Since the command signal becomes larger than the predetermined value during a rotor acceleration period, the active periods of the FET power transistors become shorter. As a result, the voltage detecting means can be prevented from detecting improperly the terminal voltages of the windings, and a stable acceleration can be attained easily.
Further, since the command signal also becomes larger than the predetermined value because of a large load torque, the active periods of the FET power transistors become shorter. As a result, the voltage detecting means can be prevented from detecting improperly the terminal voltages of the windings, and a stable rotation can also be attained even when a load torque is large.
The command signal becomes smaller than the predetermined value during a stable speed control period, and the second adjust time becomes longer. Therefore, the active periods (the active electrical angles) of the FET power transistors are made considerably longer than an electrical angle of360/Q degrees. As a result, the activation widths of the windings are made larger. It is thus possible to reduce acoustic noise and vibration of the motor with a stable rotation.
Since the change operation of the adjust time is carried out in response to the command signal, it is not necessary to provide new connecting wires for the change operation extended from the commanding means such as a speed control circuit. The configuration of the motor can thus be simplified. As a result, a motor performing a stable sensorless operation with reduced power loss, reduced vibration and reduced acoustic noise can be attained at a low cost according to the present invention.
The motor in accordance with another aspect of the present invention comprises:
a rotor which has a field part generating field fluxes;
Q-phase windings (Q is an integer of 3 or more);
voltage supplying means which includes two output terminals for supplying a DC voltage;
power supplying means having Q first FET power transistors and Q second FET power transistors for supplying a power to said Q-phase windings, each of said Q first FET power transistors forming a current path between one output terminal side of said voltage supplying means and one of said Q-phase windings, and each of said Q second FET power transistors forming a current path between the other output terminal side of said voltage supplying means and one of said Q-phase windings;
voltage detecting means for producing a detected pulse signal in response to terminal voltages of said Q-phase windings;
state shifting means for shift-holding a holding state from one state to at least one other state in sequence in response to the detected pulse signal of said voltage detecting means;
activation control means for controlling active periods of said Q first FET power transistors and said Q second FET power transistors in response to said holding state;
commanding means for producing a command signal in response to an output pulse signal of said voltage detecting means; and
switching operation means for causing at least one of said Q first FET power transistors and said Q second FET power transistors to perform high-frequency switching in response to said command signal;
and that
said activation control means produces Q-phase first activation control signals and Q-phase second activation control signals in response to said holding state of said state shifting means for controlling said active periods of said Q first FET power transistors and said Q second FET power transistors, each of said active periods being an electrical angle which is larger than 360/Q degrees,
said switching operation means produces a switching pulse signal in response to said command signal, and makes high-frequency switching operation of at least one FET power transistor among said Q first FET power transistors and said Q second FET power transistors in response to said switching pulse signal, and
said state shifting means, in cooperation with said activation control means, changes active periods of said Q-phase first activation control signals and said Q-phase second activation control signals smaller in case that said command signal is larger than a predetermined value, each of said active periods of said Q-phase first activation control signals and said Q-phase second activation control signals being an electrical angle which is larger than 360/Q degrees.
With this configuration, the switching operation means causes at least one of the FET power transistors of the power supplying means to perform high-frequency switching operation in response to the command signal. Therefore, power losses at the FET power transistors of the power supplying means can be reduced significantly, whereby the power efficiency of the motor can be improved greatly.
The voltage detecting means produces the detected pulse signal in response to the terminal voltages of the windings, the state shifting means shifts the phases of the activation to the windings in response to the detected pulse signal, and the activation control means control the active periods of the FET power transistors so as to rotate the rotor in a predetermined direction. Therefore, no position detecting element is required, and the configuration of the motor becomes simplified.
When the command signal of the commanding means becomes larger than a predetermined value, the active periods (the active electrical angles) of the first activation control signals and the second activation control signals are changed to become smaller, but each of the active periods being larger than an electrical angle of 360/Q degrees. Hence, the active periods (the active electrical angles) of the FET power transistors become shortened. Since the command signal becomes larger than the predetermined value during a rotor acceleration period, the active periods of the FET power transistors become shorter. As a result, the voltage detecting means can be prevented from detecting improperly the terminal voltages of the windings, and a stable acceleration can be attained easily.
Further, since the command signal also becomes larger than the predetermined value because of a large load torque, the active periods of the FET power transistors become shorter. As a result, the voltage detecting means can be prevented from detecting improperly the terminal voltages of the windings, and a stable rotation can also be attained even when a load torque is large.
The command signal becomes smaller than the predetermined value during a stable speed control period, and the active periods of the first activation control signals and the second activation control signals become longer. Therefore, the active periods of the FET power transistors are made considerably longer than an electrical angle of 360/Q degrees. As a result, the activation widths of the windings are made larger. It is thus possible to reduce acoustic noise and vibration of the motor with a stable rotation.
Since the change operation of the adjust time is carried out in response to the command signal, it is not necessary to provide new connecting wires for the change operation extended from the commanding means such as a speed control circuit. The configuration of the motor can thus be simplified. As a result, a motor performing a stable sensorless operation with reduced power loss, reduced vibration and reduced acoustic noise can be attained at a low cost according to the present invention.
The motor in accordance with the another aspect of the present invention comprises:
a rotor which has a field part generating field fluxes;
Q-phase windings (Q is an integer of 3 or more);
voltage supplying means which includes two output terminals for supplying a DC voltage;
power supplying means having Q first FET power transistors and Q second FET power transistors for supplying a power to said Q-phase windings, each of said Q first FET power transistors forming a current path between one output terminal side of said voltage supplying means and one of said Q-phase windings, and each of said Q second FET power transistors forming a current path between the other output terminal side of said voltage supplying means and one of said Q-phase windings;
voltage detecting means for producing a detected pulse signal in response to terminal voltages of said Q-phase windings;
state shifting means for shift-holding a holding state from one state to at least one other state in sequence in response to the detected pulse signal of said voltage detecting means;
activation control means for controlling active periods of said Q first FET power transistors and said Q second FET power transistors in response to said holding state;
commanding means for producing a command signal in response to an output pulse signal of said voltage detecting means; and
switching operation means for causing at least one of said Q first FET power transistors and said Q second FET power transistors to perform high-frequency switching in response to said command signal;
and that
said activation control means produces Q-phase first activation control signals and Q-phase second activation control signals in response to said holding state of said state shifting means for controlling said active periods of said Q first FET power transistors and said Q second FET power transistors, each of said active periods being an electrical angle which is larger than 360/Q degrees,
said switching operation means produces a switching pulse signal in response to said command signal, and makes high-frequency switching operation of at least one FET power transistor among said Q first FET power transistors and said Q second FET power transistors in response to said switching pulse signal, and
said state shifting means includes:
adjusting means for producing a timing signal after an adjust time from detection of said detected pulse signal and another timing signal after another adjust time from detection of said detected pulse signal,
shift hold means for shift-holding said holding state in response to said timing signal, and
adjust changing means for changing said adjust time and said another adjust time of said adjusting means smaller in case that said command signal is larger than a predetermined value, thereby making the product value of said adjust time and said rotational speed of said rotor smaller and the product value of said another adjust time and said rotational speed of said rotor smaller in said case, and
said voltage detecting means stops detecting of said detected pulse signal from a pulse timing of said detected pulse signal to said another adjust time by said another timing signal, said another adjust time being larger than said adjust time.
With this configuration, the switching operation means causes at least one of the FET power transistors of the power supplying means to perform high-frequency switching operation in response to the command signal. Therefore, power losses at the FET power transistors of the power supplying means can be reduced significantly, whereby the power efficiency of the motor can be improved greatly.
The voltage detecting means produces the detected pulse signal in response to the terminal voltages of the windings, the state shifting means shifts the phases of the activation to the windings in response to the detected pulse signal, and the activation control means control the active periods of the FET power transistors so as to rotate the rotor in a predetermined direction. Therefore, no position detecting element is required, and the configuration of the motor becomes simplified.
When the command signal of the commanding means becomes larger than a predetermined value, the adjust time to the output of the timing signal from the detected pulse signal is changed so that the product value of the adjust time and the rotational speed of the rotor becomes smaller. Hence, the active periods of the FET power transistors become shortened. Furthermore, when the command signal of the commanding means becomes larger than the predetermined value, the another adjust time to the output of the another timing signal from the detected pulse signal is changed so that the product value of the another adjust time and the rotational speed of the rotor becomes smaller. The stop period of the detected pulse signal detecting operation in the voltage detecting means become shortened. Since the command signal becomes larger than the predetermined value during a rotor acceleration period, the active periods (the active electrical angles) of the FET power transistors and the stop period (the stop electrical angle) of the detecting operation become shorter during acceleration. As a result, the voltage detecting means can be prevented from detecting improperly the terminal voltages of the windings, and a stable acceleration can be attained easily.
Further, since the command signal also becomes larger than the predetermined value because of a large load torque, the active periods of the FET power transistors and the stop period of the detecting operation become shorter. As a result, the voltage detecting means can be prevented from detecting improperly the terminal voltages of the windings, and a stable rotation can also be attained even when a load torque is large.
The command signal becomes smaller than the predetermined value during a stable speed control period, and the adjust time and the another adjust time become longer. Therefore, the active periods (the active electrical angles) of the FET power transistors are made considerably longer than an electrical angle of 360/Q degrees and the stop period (the stop electrical angle) of the detecting operation is made longer. As a result, the activation widths of the windings are made larger. It is thus possible to reduce acoustic noise and vibration of the motor with a stable rotation.
Since the change operation of the adjust time is carried out in response to the command signal, it is not necessary to provide new connecting wires for the change operation extended from the commanding means such as a speed control circuit. The configuration of the motor can thus be simplified. As a result, a motor performing a stable sensorless operation with reduced power loss, reduced vibration and reduced acoustic noise can be attained at a low cost according to the present invention.
The motor in accordance with the another aspect of the present invention comprises:
a rotor which has a field part generating field fluxes;
Q-phase windings (Q is an integer of 3 or more);
voltage supplying means which includes two output terminals for supplying a DC voltage;
power supplying means having Q first FET power transistors and Q second FET power transistors for supplying a power to said Q-phase windings, each of said Q first FET power transistors forming a current path between one output terminal side of said voltage supplying means and one of said Q-phase windings, and each of said Q second FET power transistors forming a current path between the other output terminal side of said voltage supplying means and one of said Q-phase windings;
voltage detecting means for producing a detected pulse signal in response to terminal voltages of said Q-phase windings;
state shifting means for shift-holding a holding state from one state to at least one other state in sequence in response to the detected pulse signal of said voltage detecting means;
activation control means for controlling active periods of said Q first FET power transistors and said Q second FET power transistors in response to said holding state;
commanding means for producing a command signal in response to an output pulse signal of said voltage, detecting means; and
switching operation means for causing at least one of said Q first FET power transistors and said Q second FET power transistors to perform high-frequency switching in response to said command signal;
and that
said activation control means produces Q-phase first activation control signals and Q-phase second activation control signals in response to said holding state of said state shifting means for controlling said active periods of said Q first FET power transistors and said Q second FET power transistors, each of said active periods being an electrical angle which is larger than 360/Q degrees,
said switching operation means produces a switching pulse signal in response to said command signal, and makes high-frequency switching operation of at least one FET power transistor among said Q first FET power transistors and said Q second FET power transistors in response to said switching pulse signal, and
said state shifting means includes:
adjusting means for producing a first timing signal after a first adjust time from detection of said detected pulse signal, a second timing signal after a second adjust time from detection of said detected pulse signal, and a third timing signal after a third adjust time from detection of said detected pulse signal, said second adjust time being larger than said first adjust time,
shift hold means for shift-holding said holding state from a first state to a second state after said first adjust time from detection of said detected pulse signal in response to said first timing signal, and further shift-holding said holding state from said second state to a third state after said second adjust time from detection of said detected pulse signal in response to said second timing signal, and
adjust changing means for changing at least said third adjust time of said adjusting means smaller in case that said command signal is larger than a predetermined value, thereby making the product value of said third adjust time and said rotational speed of said rotor smaller in said case, and
said voltage detecting means stops detecting of said detected pulse signal from a pulse timing of said detected pulse signal to said third adjust time in response to said third timing signal, said third adjust time being larger than said second adjust time and substantially proportional to an interval of said detected pulse signal.
With this configuration, the switching operation means causes at least one of the FET power transistors of the power supplying means to perform high-frequency switching operation in response to the command signal. Therefore, power losses at the FET power transistors of the power supplying means can be reduced significantly, whereby the power efficiency of the motor can be improved greatly.
The voltage detecting means produces the detected pulse signal in response to the terminal voltages of the windings, the state shifting means shifts the phases of the activation to the windings in response to the detected pulse signal, and the activation control means control the active periods of the FET power transistors so as to rotate the rotor in a predetermined direction. Therefore, no position detecting element is required, and the configuration of the motor becomes simplified.
When the command signal of the commanding means becomes larger than a predetermined value, the third adjust time to the output of the third timing signal from the detected pulse signal is changed so that the product value of the third adjust time and the rotational speed of the rotor becomes smaller. Hence, the stop period (the stop electrical angle) of the detected pulse signal detecting operation in the voltage detecting means become shortened. Since the command signal becomes larger than the predetermined value during a rotor acceleration period, the third adjust time becomes shorter and the stop period of the detecting operation becomes shorter during acceleration. As a result, the voltage detecting means can be prevented from detecting improperly the terminal voltages of the windings, and a stable acceleration can be attained easily.
Further, since the command signal also becomes larger than the predetermined value because of a large load torque, the third adjust time becomes shorter and the stop period of the detecting operation becomes shorter. As a result, the voltage detecting means can be prevented from detecting improperly the terminal voltages of the windings, and a stable rotation can also be attained.
The command signal becomes smaller than the predetermined value during a stable speed control period, and the third adjust time becomes longer. The stop period (the stop electrical angle) of the detected pulse signal detecting operation in the voltage detecting means becomes longer. Therefore, the active periods (the active electrical angles) of the FET power transistors can be made considerably longer than an electrical angle of 360/Q degrees. As a result, the activation widths of the windings can be made larger. It is thus possible to reduce acoustic noise and vibration of the motor with a stable rotation.
Since the change operation of the adjust time is carried out in response to the command signal, it is not necessary to provide new connecting wires for the change operation extended from the commanding means such as a speed control circuit. The configuration of the motor can thus be simplified. As a result, a motor performing a stable sensorless operation with reduced power loss, reduced vibration and reduced acoustic noise can be attained at a low cost according to the present invention.
The motor in accordance with another aspect of the present invention comprises:
a rotor which has a field part generating field fluxes;
Q-phase windings (Q is an integer of 3 or more);
voltage supplying means which includes two output terminals for supplying a DC voltage;
power supplying means having Q first FET power transistors and Q second FET power transistors for supplying a power to said Q-phase windings, each of said Q first FET power transistors forming a current path between one output terminal side of said voltage supplying means and one of said Q-phase windings, and each of said Q second FET power transistors forming a current path between the other output terminal side of said voltage supplying means and one of said Q-phase windings;
voltage detecting means for producing a detected pulse signal in response to terminal voltages of said Q-phase windings;
state shifting means for shift-holding a holding state from one state to at least one other state in sequence in response to the detected pulse signal of said voltage detecting means;
activation control means for controlling active periods of said Q first FET power transistors and said Q second FET power transistors in response to said holding state;
commanding means for producing a command signal in response to an output pulse signal of said voltage detecting means; and
switching operation means for causing at least one of said Q first FET power transistors and said Q second FET power transistors to perform high-frequency switching in response to said command signal;
and that
said activation control means produces Q-phase first activation control signals and Q-phase second activation control signals in response to said holding state of said state shifting means for controlling said active periods of said Q first FET power transistors and said Q second FET power transistors, each of said active periods being an electrical angle which is larger than 360/Q degrees,
said switching operation means produces a switching pulse signal in response to said command signal, and makes high-frequency switching operation of at least one FET power transistor among said Q first FET power transistors and said Q second FET power transistors in response to said switching pulse signal,
said state shifting means, in cooperation with said activation control means, changes active periods of said Q-phase first activation control signals and said Q-phase second activation control signals smaller in case that said command signal is larger than a predetermined value, each of said active periods of said Q-phase first activation control signals and said Q-phase second activation control signals being an electrical angle which is larger than 360/Q degrees, and
said voltage detecting means stops detecting of said detected pulse signal from a pulse timing of said detected pulse signal to an adjust time, the product value of said adjust time and said rotational speed of said rotor being changed smaller in said case.
With this configuration, the switching operation means causes at least one of the FET power transistors of the power supplying means to perform high-frequency switching operation in response to the command signal. Therefore, power losses at the FET power transistors of the power supplying means can be reduced significantly, whereby the power efficiency of the motor can be improved greatly.
The voltage detecting means produces the detected pulse signal in response to the terminal voltages of the windings, the state shifting means shifts the phases of the activation to the windings in response to the detected pulse signal, and the activation control means control the active periods of the FET power transistors so as to rotate the rotor in a predetermined direction. Therefore, no position detecting element is required, and the configuration of the motor becomes simplified.
When the command signal of the commanding means becomes larger than a predetermined value, the active periods (the active electrical angles) of the first activation control signals and the second activation control signals are changed to become smaller, but each of the active periods being larger than an electrical angle of 360/Q degrees. Hence, the active periods (the active electrical angles) of the FET power transistors are shortened. Furthermore, when the command signal of the commanding means becomes larger than a predetermined value, the adjust time to the output of the timing signal from the detected pulse signal is changed so that the product value of the adjust time and the rotational speed of the rotor becomes smaller. Hence, the stop period (the stop electrical angle) of the detected pulse signal detecting operation in the voltage detecting means become shortened. Since the command signal becomes larger than the predetermined value during a rotor acceleration period, the active periods of the first activation control signals and the second activation control signals and the stop period of the detected pulse signal detecting operation are changed to become smaller during acceleration. As a result, the voltage detecting means can be prevented from detecting improperly the terminal voltages of the windings, and a stable acceleration can be attained easily.
Further, since the command signal also becomes larger than the predetermined value because of a large load torque, the active periods of the first activation control signals and the second activation control signals and the stop period of the detected pulse signal detecting operation are changed to become smaller. As a result, the voltage detecting means can be prevented from detecting improperly the terminal voltages of the windings, and a stable rotation can also be attained.
The command signal becomes smaller than the predetermined value during a stable speed control period, and the active periods of the first activation control signals and the second activation control signals become considerably longer than an electrical angle of 360/Q degrees. Furthermore, the stop period of the detected pulse signal detecting operation in the voltage detecting means becomes longer. Therefore, the active periods of the FET power transistors are made considerably longer than an electrical angle of 360/Q degrees. As a result, the activation widths of the windings are made larger. It is thus possible to reduce acoustic noise and vibration of the motor with a stable rotation.
Since the change operation of the adjust time is carried out in response to the command signal, it is not necessary to provide new connecting wires for the change operation extended from the commanding means such as a speed control circuit. The configuration of the motor can thus be simplified. As a result, a motor performing a stable sensorless operation with reduced power loss, reduced vibration and reduced acoustic noise can be attained at a low cost according to the present invention.
These and other configurations and operations will be described in detail in the explanations of embodiments of the present invention.
While the novel features of the invention are set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings.